Fri,  7.06.2018 12:09:43 After bringing up chamber sense wires to nominal voltages, tracks were barely visible and had maximum amplitudes of ~40 ADCs. Raising chamber voltages by 20 V helped, but signals are still too low. Oxygen contamination is slightly higher than last year, but drift velocity amplitudes are comparable. Gating grid noise responds when removing gating grid fanout, but perhaps both the polarities are not being transfered (or something). More to come.

Sat,  7.07.2018 00:09:38 FTPC1 gating grid distribution card had several burnt resistors. Possibly it was shorted on the crate wall, as it was in the left-most slot. This was discovered by measuring an incorrect offset ("U0") voltage on the lower FTPC gating grid crate. Replaced the card, and the "U0" voltage returned to normal.

U0 voltage can be measured via DMM using: 
1) (Negative DMM probe) Terminal with the black wire (ground) on the left-most U0/2 power supply in Crate 3 (see diagram below)
2) (Positive DMM probe) Terminal with the green wire (U0   ) on the right-most U0/2 power supply in Crate 3 (see diagram below) 

Gating grid + offsets can be measured via DMM by using:
1) (Negative DMM probe) Terminal with the green wire (ground) on the "Gating Grid +" power supply in Crate 1 (see diagram below)
2) (Positive DMM probe) Terminal with the blue wire  (GG+   ) on the "Gating Grid -" power supply in Crate 1 (see diagram below) 

Gating grid - offsets can be measured via DMM by using:
1) (Negative DMM probe) Terminal with the red   wire (GG-   ) on the "Gating Grid +" power supply in Crate 1 (see diagram below)
2) (Positive DMM probe) Terminal with the green wire (ground) on the "Gating Grid -" power supply in Crate 1 (see diagram below) 

Horizontal rows of terminals on the rear of these power supplies are coupled together.

U0 for FTPCs is currently set at -109.2V (measured Nov. 1 2018, 17:00).

Desired U0 is 0.639% of nominal drift voltage. For reference:
-20 kV:   U0 = -127.8V 
-17.3 kV: U0 = -110.5V
-17.0 kV: U0 = -108.6V


FTPC Gating Grid configuration (rack XXX):
Crate 1
_________________________
5V PS    +60V PS  -60V PS
_________________________ \
                          |
                          |  
Crate 2                   |
_________________________ |
 FTPC1    FTPC2    FTPC3  /
+GG/-GG  +GG/-GG  +GG/-GG 
_________________________ \
                          |
                          |  
Crate 3                   |
_________________________ |
9V PS   U0/2 PS1 U0/2 PS2 /
_________________________

Enter in shift logbook too!